The central nervous system of the apple snail consists of a several ganglia
connected with each other by a commisura. The perikarya (cell bodies
of the nerve cells) are concentrated in these ganglia.
Some parts of the nervous system are symmetric (for example the cerebral ganglia) while
others (like the subintestinal ganlion) are not, this because of the asymmetric
construction of the snail body.
There isn't a central brain in snails like mammals have, the different ganglia
are scattered throughout the body of the snail, although mainly located in the
head.
Every ganglion enervates some specific organs with its nerves. The pedal ganglia
for example enervates the foot (Latin: pedalis) of the snail. The function of
the commisures between the ganglia are to integrate the different parts of the
nervous system. Scheme of the nervous
system: